Fumigation is a process for the management of pests, insects, nematodes and contaminants employing fumigation agents or fumigants typically in gaseous form. As an example, the transportation of goods and materials worldwide now typically requires highly regulated fumigation processes prior to the movement of goods between locations. The fumigants certified for present and future use are of highly toxic nature by design and accordingly require strict environmental control. In addition, certain classes of fumigants are greenhouse gas active. Despite this, available fumigation processes vent the active fumigant into the atmosphere and/or immediate surroundings following fumigation and rely on gas-like dispersion to achieve once again safe levels for human interaction. This severely limits the operating areas for fumigation necessitating well ventilated areas. Some fumigants retain substantial toxic activity in the environment for extended periods and can readily accumulate to unsafe levels arising from repeated use in the same location.
Some of the commercially available fumigants include methyl-bromide (MB), sulfuryl-fluoride (SF), aluminum phosphide or phosphine gas (PG), chloropicrin, methyl isocyanate, hydrogen cyanide, formaldehyde and iodoform. Other fumigants, such as organosulfur compounds (dithiocarbamate) and new proprietary fumigants are also possible; however, global policies have been formulated based on environmental concerns to restrict the number of certified fumigants available for use. As a consequence, there are substantial up-front costs in obtaining registration or certification of new fumigation agents because of these regulatory requirements.
Of the fumigants commercially used, sulfuryl-fluoride (SF) has been found to be highly effective. Unfortunately, halide-based fumigants, apart from being highly toxic, are also well known greenhouse gases (GHGs) which are also highly reactive as ozone depleting agents. Studies have shown that the worldwide measured atmospheric concentration of halide-based fumigants is rising rapidly and is well correlated to the fumigation industry use of these substances. As a result, these halide-based gases have now irreversibly accumulated in the upper atmosphere. As such, continued use of these GHG fumigants is likely to face even stricter governmental regulation worldwide to restrict their use.
These issues with fumigants and their use are in stark contrast to their essential involvement in the preparation, storage and movement of materials in the modern economy especially in the area of food production. There is therefore a need to improve the efficacy of fumigation methods and reduce the environmental impact of these processes.